The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingRemoval
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove radiator support opening cover
Remove front wheel rh
Remove no. 1 ...
Front passenger airbag assembly
Components
On-vehicle inspection
Check front passenger airbag assembly (vehicle not involved in
collision and airbag not deployed)
Perform a diagnostic system check (see page rs-
49).
With the front passenger airbag installed on the
vehicle, perform a visual check:
chec ...
Front airbag sensor
Components
On-vehicle inspection
Check front airbag sensor (vehicle not
involved in collision and airbag not
deployed)
Perform a diagnostic system check (see page rs-
49).
Check front airbag sensor (vehicle
involved in collision and airbag has not
deployed)
Perfo ...